In recent years, there has been known a technology for including an expensive, rare metal, such as indium, in a thin film formed on the surface of a glass substrate to provide, for example, a capability of cutting off (shielding) infrared rays (see a pamphlet of WO International publication No. 2004/011381 and a pamphlet of WO International publication No. 2005/095298, for example).
In the infrared shielding glass described in the pamphlet of WO International publication No. 2004/011381, use of ITO powder containing fluorine component having excellent heat resistance allows a sol-gel method to be performed even at high temperatures of 350° C. or higher. The fluorine component is introduced into an infrared cutoff film to insulate the ITO fine particles from heat.
In the infrared shielding glass described in the pamphlet of WO publication No. 2005/095298, an infrared cutoff film is formed on at least one of the surfaces of a glass substrate. The infrared cutoff film has an organic-inorganic composite film obtained by compositing an organic substance and an inorganic oxide and ITO fine particles as an infrared cutoff component contained in the composite film.
However, when any of the infrared shielding glass described in the pamphlets of WO International publication No. 2004/011381 and WO International publication No. 2005/095298 is applied to, for example, a window glass for a railroad vehicle, it is a principal object to efficiently cut off infrared rays impinging on passengers sitting on window seats most susceptible to sunlight exposure.
Increasing the film thickness of the whole infrared cutoff film to enhance the infrared cutoff effect disadvantageously increases the cost of manufacturing the infrared shielding glass.
An object of the present invention is to provide a vehicle window glass that can be manufactured at low cost and can efficiently cut off infrared rays impinging on passengers sitting on window seats most susceptible to sunlight exposure, and a manufacturing method for the same.